[UninspiredName]

1: I usually build a fort either A: To defend choke points or get recruits or B: If there are five or more fortless allied provinces between this and the last one. And you do build different forts depending on the location. On plains you'll build Fortified Cities, which are ridiculously expensive but have a good admin value and defense. In forests, you'll build Forest Ramparts which are the opposite. There's one for just about every type of terrain.

2: For getting gems you don't need, I'll assume you're talking about random events. Those aren't your real gem income, but you can see your gems coming in per turn under magic/laboratory, then Magic Resource Treasury. As for tranferring them, once they're in a laboratory (As magic sites automatically put them) you can take them out of any laboratory you have anywhere.

3: You'll find most combat spells in the Evocation school, and can further maximize your damage output by scripting the mages to cast what you need. At level three you get a particularly noteworthy spell called Blade Wind, that requires a level 3 Earth mage. It will decimate any lightly armored troops. But yes, without researching new ones, you're stuck with mostly useless spells.

4: Depends on your strategy, really. If you have a really high dominion, a supercombatant can benefit from it. It's also the main way to get access to the Holy 4 and Holy 5 spells. Usually, though, I find it's best to put it on someone who you really want to be able to build Temples/preach (For the latter, possibly in enemy provinces). Usually I prophetize my starting commander before he starts taking down independents.

5: Blood Slaves are like the Gems of any other school. Blood Magic can be worth it, or it can not. Many times depending on your nation's access to Blood Magic and national Blood spells. As a whole, for a nation with no recruitable Blood mages, you'd be better off with Conjuration.

6: Dominion is a tricky thing. It may seem like a benefit, and it is in some ways, but any of your troops fighting there take a hit on Morale. That's minor compared to its other risk, however. If you have no Dominion of your own (White candles), you lose the game. Just like that. Temples spread your dominion, as do priests under the Preach command. Depending on your pretender's Dominion Strength, this will be either easier or harder to do, and it can get bad enough that once, with half the world under my control and temples in every province, I got dominion killed because my pretender had Dominion Strength 1.

7:The only of these commands that are reliant on having an army with you is Patrol and Pillage, and for most of the others you'd technically want mages, not commanders. You're right, though, that going alone is usually better unless you're worried about getting attacked.

8: That depends. Many people (including me) actually find it profitable to give their pretender magic that their nation doesn't have, to round out the spell they have access to. Still, if you plan on casting spells your recruitable mages have difficulty accessing, it's many times a good idea to build a Pretender around casting them. Remember, though, all it takes is one magic item, costing ten magic gems to get a Water 2 mage to cast a Water 3 spell.